STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO ANDINCLUDING 33kV PART B-05 TITLE: SPECIFICTION NO: INCEPTION DATE: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV B-05 AFTER GAZETTING (WORKING DOCUMENT FOR A 3 YEAR PERIOD) AMENDMENTS / REVISIONS DATE PAGE PARAGRAPH DESCRIPTION ORIGINATOR APPROVED Infrastructure Technical Standards Page B-05:1 ...... UNDERGROUND CABLE AND CABLE ACCESSORIES FOR MEDIUM VOLTAGES UP TO AND INCLUDING 33KV.........................................................3 2.......................6 XLPE DISTRIBUTION CABLES ....................................13 4.........................3 3..........................................................5 4........ 3 2................ 8 CABLE TERMINATIONS (3..................................................................................6.. 6........................................................................................................................3 4.........................................7 4............................................3...9 4......... 10 HANDLING AND LAYING OF UNDERGROUND CABLES UP TO AND INCLUDING 33KV....................... 11 CABLE ROUTES AND POSITIONING ...........................................................................................4 3.......................6 4....................................... UNDERGROUND CABLE AND CABLE ACCESSORIES FOR LOW VOLTAGES UP TO AND INCLUDING 400V........................................................ 22....3......................................................................................... SCOPE ........................................2 3................................ 9 SINGLE CORE LV CABLES/CONDUCTORS ................................................. 11...........STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV TABLE OF CONTENTS PAGE 1................................................... ....2 2......................................................... 7 CABLE ACCESSORIES (3..1 2...............................10 4... 6............ 14 PROTECTION OF CABLES ................. 9 LV CABLE JOINTS AND TERMINATIONS ...................... 6 2....................................15 4.....................................3........... 13 LAYING ....................................................................................................................................................11 4.............5 2...... .................................... 11 HANDLING AND LAYING OF CABLES ........................... 8 3......8 4..................................................................................... 12 BEDDING ............. 15 KICK PIPES ................................ 15 TRENCH EARTH WIRES ................... 6.. ................ 33KV) ...........................................6....................................................................................... 6 PVC DISTRIBUTION CABLES .................. 33KV) ....... ARMOURED 4-CORE LV CABLES .......................................16 GENERAL.............. 13 BACKFILLING................................................................................................................... 16 Infrastructure Technical Standards Page B-05:2 ..14 4....................5 4.................. 15 SEALING OF ENDS.............................................................. 15 5.....................................12 4............................................................................................... 14 SLEEVES/CABLE DUCTS ..1 4.......................................................................... 22..... 9 LV CABLES AND CONDUCTOR ACCESSORIES ................ 11................ 11..........................................................................................................................6........................ INSTALLATION OF EARTHING SYSTEMS FOR UNDERGROUND CABLES......................... 14 OPENING UP OF EXISTING CABLES ................................................................................... 6 PILC DISTRIBUTION CABLES .......................................................................................... 9 3...........................................................................................2 4........ 9 BARE STRANDED COPPER CONDUCTOR ............ 11 TRENCHING ................................................................. 22............................ 14 ROAD CROSSINGS ....................................... 7 CABLE JOINTS (3... 14 CAPACITY OF CABLE CONDUITS (SLEEVES) .......................................................................4 4.................................................1 3............................ ........................... 15 CABLE MARKERS ..................................................4 2................................ 33KV) ........................................................... 11 4.. for the safety of persons : Recommended maintenance policy for electricity networks : Overhead power lines for conditions prevailing in South Africa NRS 059 NRS 060 NRS 082 SANS 10280 Infrastructure Technical Standards Page B-05:3 . using wooden pole structures and bare conductors. testing and commissioning of medium and low voltage underground cables in accordance with the following standards listed below: GENERAL INFORMATION The following Standards and Acts shall take precedence: National Electricity Act of Namibia Quality of Service Standard Quality of Supply Standard NamPower Specifications for the Erection of Overhead Power Lines NamPower Specifications and General Conditions for Survey and Route Clearing for New Power Lines The following Standard shall be used as reference: NRS 033 : Electricity Distribution – Guidelines for the application design. planning and construction of medium voltage overhead power lines up to and including 33kV. installation. SCOPE This part of the specification deals with the material requirements.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 1. NRS 034 NRS 043 : Code of practice for the joint use of structures for power and telecommunication lines : Recommendations to minimize problems associated with the theft of transformer neutral and neutral earthing copper conductors : Code of practice for clearances for electrical systems with rated voltages up to and including 145kV. : Guidelines for the provision of electrical distribution networks in residential areas. flame retardant materials : Materials of insulated electric cable and flexible cords Part 6: Armour : Materials of insulated electric cable and flexible cords Part 7: Polyethylene (PE) : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 1: General : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 2: Wiring cables : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 3: PVC Distribution Cables : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 4: XLPE Distribution Cables : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 5: Halogen-free distribution cables : Electric cables with extruded solid dielectric insulation for fixed installations (300/500V to 1900/3300V) Part 6: Service Cables SANS 1411-3 SANS 1411-4 SANS 1411-5 SANS 1411-6 SANS 1411-7 SANS 1507 SANS 1507-1 SANS 1507-2 SANS 1507-3 SANS 1507-4 SANS 1507-5 SANS 1507-6 SANS 10198-1 : The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 1: Definitions and statutory requirements SANS 10198-2 : The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 2: Choice of cable type and methods of installation SANS 10198-3 : The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 4: Current ratings Infrastructure Technical Standards Page B-05:4 .STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV UNDERGROUND DISTRIBUTION CABLES Regional Standards NRS 013 NRS 074 SANS 1411-1 SANS 1411-2 : Medium voltage cables : Low voltage (600/1000 V) cable systems for underground electrical distribution : Materials of insulated electric cable and flexible cords Part 1: Conductors : Materials of insulated electric cable and flexible cords Part 2: Polyvinyl Chloride (PVC) : Materials of insulated electric cable and flexible cords Part 3: Elastomers : Materials of insulated electric cable and flexible cords Part 4: Cross-linked Polyethylene (XLPE) : Materials of insulated electric cable and flexible cords Part 5: Halogen free. handling and installation of electric power cables of rating not exceeding 33kV Part 3: Earthing systems – general provisions SANS 10198-4 : The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 7: Safety Precautions SANS 10198-8 : The selection. lighting and internal wiring : Low Frequency Cables and wires with PVC Sheeth : Paper Insulated Metal-Sheathed Cables for Rated Voltages up to 36kV : Guide to the selection of high voltage cables : Polyvinyl chloride insulated cables of rated voltages up to and including 1kV : Conductors of insulated cables : Power cables with extrudedinsulation and their accessories for rated voltages from 1kV up to and including 36kV Infrastructure Technical Standards Page B-05:5 .8/6. handling and installation of electric power cables of rating not exceeding 33kV Part 13: Testing.Impregnated paper insulated metal sheathed cables for rated voltages 3.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV SANS 10198-5 : The selection.6kV to 19/33kV SANS 1339 International Standards BS 6004 IEC 60189 IEC 60055 IEC 60183 IEC 60227 IEC 60228 IEC 60502 : Electric cables. handling and installation of electric power cables of rating not exceeding 33kV Part 5: Determination of thermal and electrical resistivity of soil SANS 10198-6 : The selection.Cross linked polyethylene (XLPE) insulated cables for rated voltages 3. handling and installation of electric power cables of rating not exceeding 33kV Part 10: Jointing and termination of paper-insulated SANS 10198-11: The selection.3kV SANS 10198-10: The selection.3kV to 19/33kV (Excluding pressure assisted cables) : Electric cables. handling and installation of electric power cables of rating not exceeding 33kV Part 9: jointing and termination of extruded solid dielectric insulated cables up to 3. handling and installation of electric power cables of rating not exceeding 33kV Part 6: Transportation and storage SANS 10198-7 : The selection. for electric power. handling and installation of electric power cables of rating not exceeding 33kV Part 11: Jointing and termination screened polymeric insulated cables SANS 10198-12: The selection. non-armoured cables for voltages up to and including 450/750 V. commissioning and fault location SANS 10198-14: The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 14: Installation of aerial bundled conductor (ABC) SANS 97 : Electric Cables. handling and installation of electric power cables of rating not exceeding 33kV Part 12: Installation of earthing system SANS 10198-13: The selection. handling and installation of electric power cables of rating not exceeding 33kV Part 8: Cable laying and installation SANS 10198-9 : The selection.3/3. PVC insulated. extruded semi-conductive conductor screen.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 2. binder tape and covered with a non-permeable PVC sheath Conductor material Insulation Number of cores Operating voltage Type Construction 2. extruded semi-conductive core screen. and SANS 10198-4 Stranded copper or aluminium XLPE in accordance with SANS 1411-4 3 up to 33 kV depending on design specifications A or B (individually screened) Conductor. XLPE insulation. 2. and SANS 10198-4 Stranded copper or aluminium PVC in accordance with SANS 1411-2 3 up to 3. UNDERGROUND CABLE AND CABLE ACCESSORIES FOR MEDIUM VOLTAGES UP TO AND INCLUDING 33KV.1 XLPE Distribution Cables The cable shall be of the cross linked polyethylene (XLPE) insulated type in conformity with SANS 1339. The three cores laid up with fillers. SANS 1507-4 and NRS 013 Conductor size As required for Design Specifications and in accordance with SANS 10198-2. individual core copper tape earth screen.3 kV depending on design specifications A or B (individually screened) copper conductor insulated with compounds of polymers or of co-polymers of vinyl chloride (PVC) Conductor material Insulation Number of cores Operating voltage Type Construction Infrastructure Technical Standards Page B-05:6 . Conductor size As required for Design Specifications and in accordance with SANS 10198-2.2 PVC Distribution Cables The cable shall be of the Polyvinyl Chloride (PVC) insulated type in conformity with NRS 013 and SANS1507-3. core identification. three core screened cables of rated voltages 6. 6. or drained general purpose.3. general purpose. or drained general purpose. Reference shall be made to SANS 10198-5 when determining thermal and electrical resistivity of soil. 6. 33kV) The cable accessories shall be designed to ensure satisfactory operation under the site conditions specified and under normal and fault conditions. Fully impregnated. three core belted cables of rated voltages 3. heavy duty. Fully impregnated.35/11kV. Conductor material Insulation Number of cores Operating voltage Type Construction 2. 6. 3.3 PILC Distribution Cables The cable shall be of the Paper Insulated Lead Sheathed Cable (PILC) type in conformity with NRS 013 and SANS 97. Fully impregnated.6/6. single core cables of rated voltages 3. Fully impregnated.8/6. Cable laying accessories shall conform to SANS 10198-8.8/6. 12.6/6. 22. heavy duty.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 2. 12. Conductor size As required for Design Specifications and in accordance with SANS 10198-2.35/11kV.35/11kV .7/22kV and 19/33kV.8/6. general purpose. All current carrying connectors and insulating materials shall be of ample section and surface area and shall have been tested for carrying the currents and for providing the insulation corresponding to the cable size specified.3kV. three core belted cables of rated voltages 3.8/6.6kV.3/3.35/11kV and 11/11kV.35/11kV .6. three core screened cables of rated voltages 6.6kV and 6.4 Cable Accessories (3. or drained general purpose. Infrastructure Technical Standards Page B-05:7 . The following cables are covered by this standard: Fully impregnated. 11.7/22kV and 19/33kV. single core cables of rated voltages 3.6kV .6kV. 6. and SANS 10198-4 Copper or Aluminium and Lead Sheaths Paper in accordance with SANS 97 3 up to 33 kV depending on design specifications A or B (individually screened) Single core or three core impregnated paper insulated metal sheathed cables.6kV .35/11kV and 11/11kV. 6.6kV 6. general purpose. Fully impregnated. heavy duty. Terminations shall be suitable for terminating the cable at terminals on switchgear and transformers positioned outdoor and indoor. 22. All stress relieving field guide and insulating materials as well as boots and sleeves for obtaining a complete installation. 6. all insulating. 11. : Jointing and termination of screened polymeric insulated cables.4 below. Approved joints as per item 3. : Jointing and termination of screened polymeric insulated cables. 6. The following standards are to be adhered to: SANS 10198-10 SANS 10198-11 : Jointing and termination of paper insulated cables. electrical field stress relieving and jointing materials.4 below shall be used.3. The following standards shall be adhered to: SANS 10198-10 SANS 10198-11 : Jointing and termination of paper insulated cables. Each kit shall be packed in a separate box containing all materials required to make a complete installation.5 Cable Joints (3. Infrastructure Technical Standards Page B-05:8 . 22.3.6 Cable Terminations (3. for XLPE type cables. conductor jointing sleeves (ferrules) and instructions. Through joints shall be suitable for jointing the cable specified supplied with sleeve.6. and on overhead lines. 33kV) The cable terminations shall be terminated using heat shrink type approved cables by the engineer in accordance with NRS 013. 11. 33kV) Cable through joints shall be of the heat shrink type approved by the Engineer as per item 3. The terminations shall be supplied in kit form complete with gland.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 2. 2.6. STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 3. The bare stranded copper conductors shall be supplied and delivered in rolled lengths. The conductor shall be of high conductivity annealed stranded copper.4 LV cable joints and terminations Joints in underground cables.3 Bare stranded copper conductor (a) (b) (c) Bare stranded copper conductors shall be used as earth continuity conductors. The bedding shall consist of a continuous impermeable sheath of PVC extruded to fit the core or cores closely and in the case of multi-core cables. The insulation shall be general purpose PVC. 3. The conductors shall be of hard drawn stranded copper compliant to SANS 182. to fill the interstices between cores. Each end of the cables to Infrastructure Technical Standards Page B-05:9 .2 Single core LV cables/conductors Single core cables and conductors shall be manufactured in accordance with SANS 1507. shall be made by means of approved epoxyresin pressure type jointing kits or products equally approved by the Engineer.1 Armoured 4-core LV cables Cables shall be manufactured in accordance with SANS 1507 and shall be constructed as follows: (a) Armoured cables: PVC-insulated/PVC-bedded/steel wire armoured/black extruded PVC onto sheath (PVC/PVC/SWA/PVC). The PVC insulation shall be ultra violet stabilized and manufactured to SANS 1411 Part 2. 600/1000V grade. and terminations. The insulation shall be general purpose PVC. 3. The PVC insulation and covering shall be ultra violet stabilized and manufactured to SANS 1411 Part 2. Joints must be made by competent cable jointers and entirely in accordance with the manufacturer’s instructions using only the materials stipulated in such instructions. and shall be constructed as follows: (a) (b) PVC insulated/unsheathed in accordance with SANS 1411 Part 2. 600/1000 V grade. Armouring shall consist of one layer of galvanized steel wire in the case of multi-core cables and shall conform to SANS 1411 Part 6. UNDERGROUND CABLE AND CABLE ACCESSORIES FOR LOW VOLTAGES UP TO AND INCLUDING 400V. (c) (d) 3. (b) (c) (d) (e) 3. The shrouds shall be made of non-deteriorating neoprene or other synthetic rubber.1 LV cables and conductor accessories Cable glands for armoured cable (a) Glands to be used for terminating PVC/PVC/SWA/PVC cables shall be of the adjustable type. Infrastructure Technical Standards Page B-05:10 . oil and sunlight. The shrouds shall fit tightly around the glands and cable. (b) The cable hood shall be suitable for mounting onto a wood pole.5 3.5. for cable sizes above 50mm² cable boots shall be used.5. All cable lugs and ferrules shall comply with NRS 028 and IEC 61238. and shall be resistant to water. Non-watertight glands must be easily converted to watertight glands by means of a waterproofing shroud and inner seal kit.2 Cable termination lugs Termination lugs shall be tinned copper brand for copper conductors. approved by the engineer. LV cables shall be made off with sealing glands and materials specially designed for this purpose in compliance with SANS 10198-9.) The tenderer must include specifications of the cable hood offered. (b) (c) (d) (e) (f) (g) (h) (i) 3. The glands shall consist of a barrel carrying a cone bush screwed into one end and a nickel-plated brass nipple carrying a nickel-plated brass or a heavy galvanized steel locknut screwed into the other end. Each gland shall be supplied with a shroud and water-proofing kit. The glands shall be made of nickel-plated bronze. On the cable entry side of the barrel a concave groove shall be provided to accommodate the top rim of the waterproofing shroud. Glands shall be provided with ISO threads and shall be suitable for the specified cable sizes.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV be jointed must have a minimum of 1000mm of slack disposed in a loop without stress. 3.3 Cable hoods (a) Cable hoods for the protection of the cable terminations at tap-offs from the overhead ABC conductors to an underground cable shall be used (from 35mm² up to 50mm² x 4-core cable. Backfilling under joints must be firmly tamped to prevent any subsequent settling. The galvanizing shall comply with SANS 121. Glands shall be suitable for general purpose 600/1000V grade 4-core cable with steel armouring. 3.5. Glands shall be brands approved by the engineer in accordance with SANS 1213. 1 General Cable work shall be done in accordance with SANS 10198 and to the satisfaction of the Client and the Engineer. where necessary. (2) (3) Infrastructure Technical Standards Page B-05:11 . fix in position clamp and saddle where required to walls. The contractor shall be responsible to draw in.2 Cable routes and positioning The contractor shall follow the routes indicated on the specification drawings as accurately as possible. Laying depths of cables specified are to final levels of the streets and sidewalks. will be rejected. boundaries. it shall be supported at points at such a distance apart that the cable is not dragged along the ground and that it is not kinked. In particular. 4. attention is drawn to the following: (1) Cable drums shall not be dropped off transport vehicles but shall be hoisted off with approved equipment. The cable route drawings issued with the inquiry documents are for tender purposes only and the routes may be amended before work on any particular section of the route commences. Best accepted practice is to be adopted in the handling and laying of cables and the work shall be carried out by persons experienced in the class of work. Cable shall be rolled off drums in the indicated direction. The storage. 4. HANDLING AND LAYING OF UNDERGROUND CABLES UP TO AND INCLUDING 33KV. lay. Deviations from the routes laid down shall not be made without the engineer’s approval. and other services shall. or cables damaged in any other way. 4. All levels shall be obtained by the contractor from the Local Authority. circumvent obstacles. thread through pipes. transportation. be indicated to the contractor by the engineer on site and shall be strictly adhered to.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 4. Twisted or kinked cables. the drums being supported on approved equipment.3 Handling and laying of cables The contractor must satisfy himself that the levels of the trenches excavated are suitable and are wide enough to enable him to carry out the work in accordance with SANS 10198-8. cables shall circumvent such obstacles by being laid in as smooth a path as possible around the obstacles and by retaining maximum separation between cables. handling and laying of underground cables shall conform to SANS 10198 and to BS 6004. poles or switch gear all cables set out in the contract. In general. and the Contractor shall have adequate and suitable equipment (SANS 10142) and labour to ensure that no damage is done to cables during such operations. where obstacles not provided for in the specification drawings are encountered. When cables are laid out. The final position of cable relative to kerbs. Cables shall be rolled off drums in the same direction.4 Trenching 11kV cables shall generally be laid at a minimum depth of 1000mm below ground level. including suitable cable harnesses. Streetlight cables buried in trenches under un-tarred roads shall be buried in a trench with minimum depth of 600mm and 300mm wide. The engineer’s decision shall be final. quantity and required spare quantities. roads. and normally in HDPE corrugated sleeving of applicable size. Cables shall not be bent in any event to radii smaller than 15 times the overall diameter of the cable. Infrastructure Technical Standards Page B-05:12 .STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV (4) Cables shall be drawn into position or laid. unless otherwise instructed. to prevent corresponding phase cores being crossed at joints. Trenches shall not be less than 300mm wide for single and multiple LV service connection cables. shall be used. and to safeguard all structures. (5) (6) (7) 4. The Contractor must take all the necessary precautions to prevent trenching work being in any way a hazard to the public. Soil type shall be graded by the engineer. Trenches under tarred roads shall be buried a minimum of 500mm deep. Such authority shall be given in writing. Main LV feeder cables. the engineer may authorize trenches not less than 500mm deep. for negotiating corners to avoid excess bending or damage to the cable. shall be laid at a minimum depth of 800mm below ground level. sewer works or other property from any risk of subsidence and damage. Cables shall be drawn through cable pipe sleeves so as to ensure minimum damage to cables. Where the nature of the ground does not permit the excavation of the cable trenches to the specified depth. Approved equipment. and the trench width shall be increased where more than two LV feeder or service connection cables are laid together so that the cables may be placed at least 150mm apart throughout the run. railways. using a sufficient number of rollers and suitable equipment. tension or mechanical damage is caused. 400V feeder. Particular care must be exercised where it is necessary to draw cables through pipes and ducts.5 Bedding All cables shall be laid in a bedding of soft sand or sifted soil.5m long x 1.4.22.6 Laying Cable shall be removed from the drum in such a way that no twisting. to avoid abrasion. TRENCH DETAIL FOR CABLE SETUP NEEDED Single 11. 4. 50mm below and 150mm above the cable.33kV 3 Parallel 11. the pit shall be 3m x 2m for two joints. 22 and 33kV.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV The following table represents the minimum standards to be applied in respect of 11.33kV 2 Parallel 11.1 TRENCH DEPTH TRENCH WIDTH Width between 11.22. 400V Street light and 230V service connection cables.22.2m and shall be rectangular in shape and large enough for the cable jointer to work comfortably and in an efficient manner. The ends of such pipes and ducts shall be sealed to approval after the drawing in of the cables. The cost to excavate joint chambers shall be allowed for in the trenching rate as part of the Bill of Quantities and shall be based on a quantity to be same as the measured through joints. Infrastructure Technical Standards Page B-05:13 . 4. The minimum size of a joint pit shall be 2. and must be adequately supported at short intervals during the whole operation. Clay soil will not be accepted as bedding. elongation or distortion of any kind.5m wide.33kV Single 400V Feeder 2 parallel 400V Feeder 3 parallel 400V Feeder Single/multiple service connections Streetlight– Un-tarred Streetlight– Tarred Combination of Multiple Cables Combination of single cables 4.22.33kV Cable n/a 600mm 600mm n/a n/a n/a n/a Width between 400V Cable n/a n/a n/a n/a 150mm 150mm None 1000mm 1000mm 1000mm 800mm 800mm 800mm 600mm 450mm 800mm 1400mm 450mm 450mm 600mm 300mm 600mm 500mm 800mm 800mm 300mm 300mm 1200mm 700mm n/a n/a 500mm n/a None None 150mm 150mm Excavation of joint chambers Jointing pits shall be excavated to a depth of 1. . After installation of the sleeves the trench shall be backfilled and tamped down in layers of 50mm to achieve a density of 95% modified AASHTO. cable sleeves shall be installed at a minimum depth of 1000mm.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV 4. for example under roads. and the material is to be tamped down after the addition of every 150mm. Sleeve end positions shall be marked with an approved cable marker. The surface is to be made good as required. The danger tape shall be 150mm wide yellow plastic with lightning flash printed onto the tape at intervals. On completion of the installation of sleeves all ends shall be sealed to prevent the ingress of dirt and moisture.7 Backfilling Backfilling after bedding is to be carried out with a proper grading of the material to ensure settling without voids. The pipe shall be supplied in 6m lengths. a letter “E” shall be cut on either side of the road on the kerbstones where these are in existence. Unless otherwise specified two additional sleeves all of the same size shall be installed for future use at each road crossing. pipes.10 Opening up of existing cables Where it is necessary to expose existing buried cables for any purpose. 4. etc. and as instructed by the Engineer. 4. 2. (b) (c) (d) 4. a concrete layer shall be placed over the bedding layer in order to give the cable additional protection. Infrastructure Technical Standards Page B-05:14 . 4.11 Sleeves/cable ducts (a) (b) uPVC Class 6 pipes shall be used as sleeves/cable ducts.0mm in diameter shall be installed in all sleeves and shall protrude 1500mm on each side of the sleeve. after installation of the cables the sleeves shall be resealed. The tape shall comply with SANS 1091. or when excavating in the vicinity of existing buried cables. The Contractor shall be responsible for making good any damage caused by his work.9 Road Crossings Cable sleeves for road crossings shall not be installed less than 1000mm below the final street level. At road crossings. Where so directed by the Engineer.8 Protection of cables (a) Danger tape to specification shall be placed 400mm above all MV and main feeder cables along the entire length of the trench. Galvanized steel draw wire. and duly warned by the Contractor. shall be employed thereon. every care is to be exercised and only labourers experienced in such work. as well as to local earth bars. (b) (c) 4. cable sleeves shall be installed at a minimum depth of 1000mm. Infrastructure Technical Standards Page B-05:15 . The BCEW shall have a cross sectional area equal to at least half that of one phase conductor of the cable. One spare sleeve per cable duct is to be installed and plugged with PVC sheeting.12 Capacity of cable conduits (sleeves) Where cables are to be drawn into sleeve pipes separate cable conduit runs are to be provided for each main distribution cable. 4. Joints in the cable shall be marked and the maximum distance between route markers shall not exceed 100m. branch earth wires being brazed on where required.14 Trench earth wires Bare copper earth wire is to be run with all underground cables constituting part of a low voltage distribution system. 3 service cables or main cable plus street lighting and/or service cable.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV (c) One end of each pipe and bend shall be fluted to form a female coupling so that pipes can be easily joined.72mm stainless steel bandit strapping shall be used for fixing of kick pipes against poles. The earth continuity conductor is to be bonded to the cable armouring at each termination of the cable.e. the ends are to be sealed without delay. Coastal or corrosive environments may require stainless steel rod together with multiple point earthing distribution points. 20mm x 0. and as instructed by the Engineer.16 Cable markers Cable route markers of approved manufacture shall be provided at each end of an underground cable route and at all points where such routes deviate from a straight line. 4. but shall not be less than 10mm². The maximum number of cable to be accommodated in a single cable conduit shall be 3 plus the trench earth i.13 Kick pipes (a) HDPE Class 6 pipes shall be used as kick pipes for distribution cables on poles. 4. A single earth conductor shall be used as earth continuity conductor for two or more cables run together. Galvanized steel saddles shall be used for fixing of cables against poles. (d) 4. Suitable diameter pipes shall be supplied in 3m lengths.15 Sealing of ends Where cables are cut and not immediately made off. Contractors should contact the supply authority in coastal areas or corrosive areas in order to enquire about the earthing requirements. At road crossings. Infrastructure Technical Standards Page B-05:16 . Marking of cable markers shall also be in accordance with approved detail drawings. Refer to SANS 10198-7 for earthing requirements regarding the following cable components: Metal Sheaths – Multi Core Cables Metal Sheaths – Single Core Cables Metal Screens Armour Cross Bonding Refer to SANS 10198-7 for requirements regarding Protective Multiple Earthing Cables as well as Combined / Neutral Cables. 5. INSTALLATION OF EARTHING SYSTEMS FOR UNDERGROUND CABLES.STANDARD SPECIFICATION FOR MEDIUM AND LOW VOLTAGE ELECTRICITY DISTRIBUTION WORKS PART B-05: UNDERGROUND CABLE DISTRIBUTION UP TO AND INCLUDING 33kV The cable markers shall be tapered blocks cast from concrete in accordance with approved detail drawings Each cable marker shall be buried with its upper face 100mm above the natural ground level.